Optical element

ABSTRACT

An optical element is provided. The optical element is a light-dividing element, for example an element that can divide incident light into at least two kinds of light having different polarized states. The optical element can be used to realize a stereoscopic image.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean PatentApplication Nos. 2011-0057830, filed at Jun. 15, 2011, 2010-0111758,filed at Nov. 10, 2010; 2010-0111757, filed at Nov. 10, 2010;2010-0124411, filed at Dec. 7, 2010; 2011-0110092, filed at Oct. 26,2011; 2011-0110096, filed at Oct. 26, 2011; 2011-0117232, filed at Nov.10, 2011 and 2011-0110093, filed at Oct. 26, 2011, the disclosures ofwhich are incorporated herein by reference in their entirety.

BACKGROUND

1. Field of the Invention

The present invention relates to an optical element and a stereoscopicimage display device.

2. Discussion of Related Art

Techniques of dividing light into at least two kinds of light havingdifferent polarized states may be effectively used in various fields.

The light division techniques may be, for example, applied tomanufacture of stereoscopic images. The stereoscopic images may berealized using binocular disparity. For example, when two 2-dimensionalimages are input into the human left and right eyes, respectively, theinput information is transmitted and combined in the brain, which makesit possible for a human being to experience 3-dimensional (3D) senses ofdepth and reality. Therefore, the light division techniques may be usedduring this procedure.

Techniques of generating a stereoscopic image may be effectively usedfor 3D measurements, and also used in 3D TV, cameras or computergraphics.

SUMMARY OF THE INVENTION

The present invention is directed to providing an optical element and astereoscopic image display device.

One aspect of the present invention provides an optical element. Theoptical element according to one exemplary embodiment may include aliquid crystal layer, a base layer and a polarizer, which aresequentially formed.

FIG. 1 is a cross-sectional view of an optical element 1 according toone exemplary embodiment, showing a structure of the optical element 1in which a liquid crystal layer 11, a base layer 12 and a polarizer 13are sequentially formed.

According to one exemplary embodiment, the optical element may be anelement that can divide incident light into two or more kinds of lighthaving different polarized states. Such an element may be, for example,used to realize a stereoscopic image.

The liquid crystal layer may have a difference between in-planerefractive indexes in a slow axis direction and a fast axis direction of0.05 to 0.2, 0.07 to 0.2, 0.09 to 0.2 or 0.1 to 0.2. As such, thein-plane refractive index in the slow axis direction may refer to arefractive index in a direction in which the maximum value of therefractive index is defined with respect to the plane of the liquidcrystal layer, and the in-plane refractive index in the fast axisdirection may refer to a refractive index in a direction in which theminimum value of the refractive index is defined with respect to theplane of the liquid crystal layer. In general, the fast axis and slowaxis in an optically anisotropic liquid crystal layer are formedvertically to each other. The refractive indexes may be measured withrespect to light at a wavelength of 550 nm or 589 nm.

The liquid crystal layer may also have a thickness of approximately 0.5μm to 2.0 μm or approximately 0.5 μm to 1.5 μm.

The liquid crystal layer satisfying the relationship of the refractiveindexes and having the thickness may express a phase retardationproperty suitable for use in applications. According to one exemplaryembodiment, the liquid crystal layer satisfying the relationship of therefractive indexes and having the thickness may be suitable for use inan optical element for optical division.

The liquid crystal layer may include a multifunctional polymerizableliquid crystal compound and a monofunctional polymerizable liquidcrystal compound, and the liquid crystal compounds may be included inthe liquid crystal layer in a polymerized form.

In this specification, the term “multifunctional polymerizable liquidcrystal compound” may refer to a compound that shows a liquidcrystalline property because it includes a mesogen backbone, and alsocontains at least two polymerizable functional groups. According to oneexemplary embodiment, the multifunctional polymerizable liquid crystalcompound may contain 2 to 10, 2 to 8, 2 to 6, 2 to 5, 2 to 4, 2 to 3, or2 polymerizable functional groups.

In this specification, the term “monofunctional polymerizable liquidcrystal compound” may also refer to a compound that shows a liquidcrystalline property because it includes a mesogen backbone, and alsocontains at least one polymerizable functional group.

Also, in this specification, the expression “liquid crystal compoundbeing included in a liquid crystal layer in a polymerized form” mayrefer to a state in which the liquid crystal compound is polymerized toform a liquid crystal polymer in the liquid crystal layer.

When the liquid crystal layer includes a multifunctional andmonofunctional polymerizable compound, the liquid crystal layer may havemore excellent phase retardation properties, and the realized phaseretardation properties, for example, the optical axis and a phaseretardation value of the liquid crystal layer, may be stably maintainedunder the severe conditions.

According to one exemplary embodiment, the multifunctional ormonofunctional polymerizable liquid crystal compound may be a compoundrepresented by the following Formula 1.

In Formula 1, A is a single bond, —COO— or —COO—, and R₁ to R₁₀ are eachindependently hydrogen, a halogen, an alkyl group, an alkoxy group, analkoxycarbonyl group, a cyano group, a nitro group, —O-Q-P or asubstituent of the following Formula 2, provided that at least one ofthe substituents R₁ to R₁₀ is —O-Q-P or a substituent of the followingFormula 2, or two adjacent substituents of R₁ to R₅ or two adjacentsubstituents of R₆ to R₁₀ are joined together to form a benzene ringsubstituted with —O-Q-P, wherein Q is an alkylene group or an alkylidenegroup, and P is a polymerizable functional group such an alkenyl group,an epoxy group, a cyano group, a carboxyl group, an acryloyl group, amethacryloyl group, an acryloyloxy group or a methacryloyloxy group.

In Formula 2, B is a single bond, —COO— or —COO—, and R₁₁ to R₁₅ areeach independently hydrogen, a halogen, an alkyl group, an alkoxy group,an alkoxycarbonyl group, a cyano group, a nitro group or —O-Q-P,provided that at least one of substituents R₁₁ to R₁₅ is —O-Q-P, or twoadjacent substituents of R₁₁ to R₁₅ are joined together to form abenzene ring substituted with —O-Q-P, wherein Q is an alkylene group oran alkylidene group, and P is a polymerizable functional group such asan alkenyl group, an epoxy group, a cyano group, a carboxyl group, anacryloyl group, a methacryloyl group, an acryloyloxy group or amethacryloyloxy group.

In Formulas 1 and 2, the expression “two adjacent substituents arejoined together to form a benzene ring substituted with —O-Q-P” may meanthat the two adjacent substituents are joined together to form anaphthalene backbone substituted with —O-Q-P as a whole.

In Formula 2, “-” indicated on the left side of B may mean that B isdirectly bound to the benzene ring of Formula 1.

In Formulas 1 and 2, the term “single bond” means that no additionalatoms are present in a moiety represented by A or B. For example, when Ain Formula 1 is a single bond, the benzene rings disposed on both sidesof A may be directly bound to form a biphenyl structure.

In Formulas 1 and 2, the halogen may be chlorine, bromine or iodine.

Unless otherwise defined in this specification, the term “alkyl group”may refer to a linear or branched alkyl group having 1 to 20 carbonatoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atomsor 1 to 4 carbon atoms, or a cycloalkyl group having 3 to 20 carbonatoms, 3 to 16 carbon atoms or 4 to 12 carbon atoms. The alkyl group maybe optionally substituted with one or more substituents.

Unless otherwise defined in this specification, the term “alkoxy group”may refer to an alkoxy group having 1 to 20 carbon atoms, 1 to 16 carbonatoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms or 1 to 4 carbon atoms.The alkoxy group may be linear, branched or cyclic. Also, the alkoxygroup may be optionally substituted with one or more substituents.

Also, unless otherwise defined in this specification, the term “alkylenegroup or alkylidene group” may refer to an alkylene group or alkylidenegroup having 1 to 12 carbon atoms, 4 to 10 carbon atoms or 6 to 9 carbonatoms. The alkylene group or alkylidene group may be linear, branched orcyclic. Also, the alkylene group or alkylidene group may be optionallysubstituted with one or more substituents.

Also, unless otherwise defined in this specification, the term “alkenylgroup” may refer to an alkenyl group having 2 to 20 carbon atoms, 2 to16 carbon atoms, 2 to 12 carbon atoms, 2 to 8 carbon atoms or 2 to 4carbon atoms. The alkenyl group may be linear, branched or cyclic. Also,the alkenyl group may be optionally substituted with one or moresubstituents.

Also, in Formulas 1 and 2, P may be preferably an acryloyl group, amethacryloyl group, an acryloyloxy group or a methacryloyloxy group,more preferably an acryloyloxy group or a methacryloyloxy group, andmost preferably an acryloyloxy group.

In this specification, the substituent which may be substituted with acertain functional group may be an alkyl group, an alkoxy group, analkenyl group, an epoxy group, an oxo group, an oxetanyl group, a thiolgroup, a cyano group, a carboxyl group, an acryloyl group, amethacryloyl group, an acryloyloxy group, a methacryloyloxy group or anaryl group, but the present invention is not limited thereto.

The —O-Q-P which may be present in plural numbers in Formula 1 and 2 orthe residue of Formula 2 may be, for example, present in a position ofR₃, R₈ or R₁₃. Preferably, R₃ and R₄, or R₁₂ and R₁₃ may be joinedtogether to form a benzene ring substituted with —O-Q-P. Also, in thecompound of Formula 1 or the residue of Formula 2, the substituent otherthan the —O-Q-P or the residue of Formula 2, or the substituents otherthan those being joined together to form the benzene ring may be, forexample, hydrogen, a halogen, a linear or branched alkyl group having 1to 4 carbon atoms, an alkoxycarbonyl group containing a linear orbranched alkoxy group having 1 to 4 carbon atoms, a cycloalkyl grouphaving 4 to 12 carbon atoms, an alkoxy group having 1 to 4 carbon atoms,a cyano group or a nitro group, and preferably chlorine, a linear orbranched alkyl group having 1 to 4 carbon atoms, a cycloalkyl grouphaving 4 to 12 carbon atoms, an alkoxy group having 1 to 4 carbon atoms,an alkoxycarbonyl group containing a linear or branched alkoxy grouphaving 1 to 4 carbon atoms, or a cyano group.

The liquid crystal layer may include the monofunctional polymerizableliquid crystal compound in an amount of greater than 0 parts by weightand less than 100 parts by weight, 1 part by weight to 90 parts byweight, 1 part by weight to 80 parts by weight, 1 part by weight to 70parts by weight, 1 part by weight to 60 parts by weight, 1 part byweight to 50 parts by weight, 1 part by weight to 30 parts by weight or1 part by weight to 20 parts by weight, relative to 100 parts by weightof the multifunctional polymerizable liquid crystal compound.

The mixing of the multifunctional and monofunctional polymerizableliquid crystal compounds may be maximized within this content range.Also, the liquid crystal layer may exhibit an excellent adhesiveproperty to the adhesive layer. Unless otherwise defined in thisspecification, the unit “part by weight” may mean a weight ratio.

The multifunctional and monofunctional polymerizable liquid crystalcompounds may be included in the liquid crystal layer in a horizontallyaligned state. In this specification, the term “horizontal alignment”may mean that the optical axis of a liquid crystal layer including apolymerized liquid crystal compound has an inclination angle ofapproximately 0° to approximately 25°, approximately 0° to approximately15°, approximately 0° to approximately 10°, approximately 0° toapproximately 5°, or approximately 0° with respect to a plane of theliquid crystal layer. In this specification, the term “optical axis” mayrefer to a fast axis or slow axis formed when incident light penetratesthrough a corresponding region.

The liquid crystal layer may be formed so that incident light, forexample, light passing through the polarizer, can be divided into two ormore kinds of light having different polarized states. For this purpose,the liquid crystal layer may include, for example, first and secondregions having different phase retardation properties. In thisspecification, the fact that the first and second regions have thedifferent phase retardation properties may include a case in which thefirst and second regions have optical axes formed in the same ordifferent directions and also have different phase retardation values,and a case in which the first and second regions have optical axesformed in different directions while having the same phase retardationvalue, in a state where both the first and second regions have the phaseretardation properties. According to another exemplary embodiment, thefact that the first and second regions have the different phaseretardation properties may include a case in which one of the first andsecond regions has a phase retardation property, and the other region isan optically isotropic region having no phase retardation property. Inthis case, for example, the liquid crystal layer may be formed so thatit can include both of a region including a liquid crystal material anda region free of the liquid crystal material. The phase retardationproperty of the first or second region may be regulated, for example, bycontrolling an alignment state of the liquid crystal compound, therefractive index relationship of the liquid crystal layer or a thicknessof the liquid crystal layer.

According to one exemplary embodiment, the first region A and the secondregion B may be formed in stripe shapes extending in the same directionand alternately arranged adjacent to each other, as shown in FIG. 2, orthey may be formed in a lattice pattern and alternately arrangedadjacent to each other, as shown in FIG. 3.

When the optical element is used to display a stereoscopic image, one ofthe first and second regions may refer to a region configured to controlpolarization of an image signal for the left eye (hereinafter referredto as “LC region”), and the other region may refer to a regionconfigured to control polarization of an image signal for the right eye(hereinafter referred to as “RC region”).

According to one exemplary embodiment, the two or more kinds of lighthaving the different polarized states, which are divided by the liquidcrystal layer including the first and second regions, may include twokinds of linearly polarized light having directions, which aresubstantially vertical to each other, or include left-circularlypolarized light and right-circularly polarized light.

Unless otherwise defined in this specification, when terms such asvertical, horizontal, perpendicular or parallel are used in definitionsof angles, the terms refer to an angle being substantially vertical,horizontal, perpendicular or parallel. For example, the terms includeerrors in consideration of manufacturing errors or variations.Therefore, the terms may, for example, include an error of not more thanapproximately ±15°, preferably an error of not more than approximately±10°, and most preferably an error of not more than approximately ±5°.

According to one exemplary embodiment, one of the first and secondregions may be a region through which incident light penetrates withoutrotating the polarization axis of the incident light, and the otherregion may be a region through which incident light penetrates while thepolarization axis of the incident light is rotated in a directionperpendicular to the polarization axis of the incident light whichpenetrates through the one of the first and second regions. In thiscase, the regions of the liquid crystal layer including thepolymerizable liquid crystal compound may be formed on only one of thefirst and second regions. As such, the regions in which the liquidcrystal layer is not formed may be an empty space, or may be a region inwhich a glass, or optically isotropic resin layer, resin film or sheetis formed.

According to another exemplary embodiment, one of the first and secondregions may be a region through which incident light can penetrate whenthe incident light is converted into left-circularly polarized light,and the other region may be a region through which incident light canpenetrate when the incident light is converted into right-circularlypolarized light. In this case, the first and second regions may beregions having optical axes formed in different directions while havingthe same phase retardation value, or one of the first and second regionsmay be a region in which incident light may be phase-retarded by ¼ of awavelength of the incident light, and the other region may be a regionin which incident light may be phase-retarded by ¾ of a wavelength ofthe incident light.

According to one exemplary embodiment, the first and second regions mayhave the same phase retardation value, for example, a value required tophase-retard incident light by ¼ of the wavelength of the incidentlight, and also have optical axes formed in different directions. Assuch, the optical axes formed in the different directions may be, forexample, at right angles.

When the first and second regions have the optical axes formed indifferent directions, a line bisecting an angle formed between theoptical axes of the first and the second regions is preferably drawn sothat the line can be vertical or horizontal with respect to theabsorption axis of the polarizer.

FIG. 4 is a schematic diagram explaining the arrangement of the opticalaxes of the first and second regions when the first and second regions Aand B shown in FIG. 2 or 3 have optical axes formed in differentdirections. Referring to FIG. 4, a line bisecting an angle formedbetween the optical axes of the first and second regions A and B mayrefer to a line bisecting an angle of (Θ1+Θ2). For example, when Θ1 andΘ2 are the same angle, the angle-bisecting line may be formed in adirection horizontal with respect to a boundary line L between the firstand second regions A and B. As such, an angle, namely (Θ1+Θ2), formedbetween the optical axes of the first and second regions A and B mayalso be, for example, 90°.

The above-described optical element may satisfy the conditions of thefollowing Equation 1.

X<8%  Equation 1

In Equation 1, X represents a percentage of the absolute value of avariation in a phase difference value of the liquid crystal layerobtained when the optical element is kept at 80° C. for 100 hours or 250hours, relative to the initial phase difference value of the liquidcrystal layer of the optical element.

For example, X may be calculated as follows: 100×(|R₀−R₁|)/R₀. Here, R₀is an initial phase difference value of the liquid crystal layer of theoptical element, and R₁ represents a phase difference value of theliquid crystal layer obtained when the optical element is kept at 80° C.for 100 hours or 250 hours.

X may be preferably 7% or less, 6% or less or 5% or less. A variation ofthe phase difference value may be measured using a method presented inthe following Examples.

The optical element includes a base layer with the liquid crystal layerformed thereupon. The base layer may be in a single-layer or multilayerstructure.

For example, a glass base layer or a plastic base layer may be used asthe base layer. Examples of the plastic base layer may include a sheetor film including a cellulose resin such as triacetyl cellulose (TAC) ordiacetyl cellulose (DAC); a cyclo olefin polymer (COP) such as anorbornene derivative; an acryl resin such as poly(methyl methacrylate)(PMMA); polycarbonate (PC); a polyolefin such as polyethylene (PE) orpolypropylene (PP); polyvinyl alcohol (PVA); poly ether sulfone (PES);polyetheretherketone (PEEK); polyetherimide (PEI); polyethylenenaphthalate (PEN); a polyester such as polyethylene terepthalate (PET);polyimide (PI); polysulfone (PSF); or a fluorine resin.

The base layer, for example, the plastic base layer, may have a lowerrefractive index than the liquid crystal layer. The refractive index ofthe base layer according to one exemplary embodiment is in a range ofapproximately 1.33 to approximately 1.53. When the base layer has alower refractive index than the liquid crystal layer, it is, forexample, desirable in that it enhances brightness, prevents reflectionand improves contrast characteristics.

The plastic base layer may be optically isotropic or anisotropic. Assuch, when the base layer is optically anisotropic, the optical axis ofthe base layer is preferably arranged so that the optical axis of thebase layer can be vertical or horizontal with respect to theabove-mentioned line bisecting an angle formed between the optical axesof the first region and the second region.

According to one exemplary embodiment, the base layer may include anultraviolet (UV) protector or absorbent. When the base layer includesthe UV protector or absorbent, it is possible to prevent degradation ofthe liquid crystal layer caused by UV rays. Examples of the UV protectoror absorbent may include an organic matter such as a salicylic acidester compound, a benzophenone compound, an oxybenzophenone compound, abenzotriazol compound, a cyanoacrylate compound or a benzoate compound,or an inorganic matter such as zinc oxide or a nickel complex salt. Thecontent of the UV protector or absorbent in the base layer is notparticularly limited, and may be properly selected in consideration ofdesired effects. For example, in the manufacture of the plastic baselayer, the UV protector or absorbent may be included in an amount ofapproximately 0.1% by weight to 25% by weight, relative to the weightratio of the main material of the base layer.

A thickness of the base layer is not particularly limited, and may beproperly regulated according to a desired purpose of use. The base layermay have a single-layer or multilayer structure.

The optical element according to one exemplary embodiment may furtherinclude an alignment layer disposed between the base layer and theliquid crystal layer. The alignment layer may serve to align a liquidcrystal compound during formation of the optical element. As thealignment layer, a conventional alignment layer known in the art, forexample, an optical alignment layer or a rubbing alignment layer may beused. The alignment layer is an optional configuration, and an alignmentproperty may be granted without using an alignment layer by directlyrubbing or elongating the base layer.

The polarizer formed in a bottom portion of the base layer of theoptical element is a functional element that can extract light vibratingin one direction from incident light while vibrating in variousdirections. For example, a conventional polarizer such as a PVApolarizer may be used as the polarizer.

According to one exemplary embodiment, the polarizer may be a PVA filmor sheet in which a dichroic dye or iodine is absorbed and aligned. ThePVA may, for example, be obtained by gellation of a polyvinylacetate.Examples of the polyvinylacetate may include a monopolymer of vinylacetate; and a copolymer of vinyl acetate and another monomer. As such,examples of the other monomer copolymerized with vinyl acetate mayinclude at least one selected from an unsaturated carboxylic acidcompound, an olefin compound, a vinylether compound, an unsaturatedsulfonic acid compound and an acrylamide compound having an ammoniumgroup. A gelling degree of the polyvinylacetate may generally be in arange of approximately 85 mol % to approximately 100 mol %, or 98 mol %to 100 mol %. A polymerization degree of the PVA used in the polarizermay generally be in a range of approximately 1,000 to approximately10,000, or approximately 1,500 to approximately 5,000.

According to one exemplary embodiment, the polarizer may be attached tothe base layer by means of a water-based adhesive. FIG. 5 shows anoptical element 5 according to one exemplary embodiment in which apolarizer 13 is attached to a base layer 12 by means of a water-basedadhesive 51. As such, the water-based adhesive may be used withoutparticular limitation as long as it can realize a proper adhesiveproperty. According to one exemplary embodiment, a polyvinylalcohol-based water-based adhesive generally used to attach a polarizerto a protective film of the polarizer, that is, attach a PVA-basedpolarizer to a triacetyl cellulose (TAC) film in manufacture of apolarizing plate, may be used as the water-based adhesive.

The optical element may further include a surface-treated layer formedon a top portion of the liquid crystal layer. FIG. 6 shows an opticalelement 6 according to one exemplary embodiment in which asurface-treated layer 61 is formed on a top portion of a liquid crystallayer 11.

Examples of the surface-treated layer may include a high-hardness layer,an glare-preventing layer such as AG (anti-glare) layer or SG(semi-glare) layer, or a low reflective layer such as AR (antireflection) or LR (low reflection) layer.

The high-hardness layer may have a pencil hardness of 1H or more or 2Hor more at a load of 500 g. The pencil hardness may be, for example,measured according to the ASTM D 3363 standard using pencil leadsprescribed in KS G 2603.

The high-hardness layer may be, for example, a resin layer having highhardness. The resin layer may, for example, include aroom-temperature-curable, moisture-curable, thermocurable or activeenergy ray-curable resin composition in a cured state. According to oneexemplary embodiment, the resin layer may include a thermocurable oractive energy ray-curable resin composition, or an active energyray-curable resin composition in a cured state. In description of thehigh-hardness layer, the term “cured state” may refer to a state wherecomponents included in each resin composition are subjected to across-linking reaction or a polymerization reaction to convert the resincomposition into a hard state. As such, the room-temperature-curable,moisture-curable, thermocurable or active energy ray-curable resincomposition may also refer to a composition whose cured state may beinduced at room temperature or induced in the presence of suitablemoisture or by application of heat or irradiation with active energyrays.

A variety of resin compositions which can satisfy this range of pencilhardness when they are cured are known in the art, and a suitable resincomposition may be readily selected by a person of ordinary skill in theart.

According to one exemplary embodiment, the resin composition may includean acryl compound, an epoxy compound, a urethane-based compound, aphenol compound or a polyester compound as a main component. As such,the term “compound” may be a monomeric, oligomeric or polymericcompound.

According to one exemplary embodiment, an acryl resin composition havingexcellent optical properties such as transparency and superior yellowingresistance, preferably an active energy ray-curable acryl resincomposition, may be used as the resin composition.

The active energy ray-curable acryl composition may, for example,include an active energy ray-polymerizable polymer component and areactive diluting monomer.

As such, examples of the polymer component may include a componentgenerally known in the art as an active energy ray-polymerizableoligomer, such as urethane acrylate, epoxy acrylate, ether acrylate orester acrylate, or a polymerization product of a mixture including amonomer such as a (meth)acrylic ester monomer. As such, examples of the(meth)acrylic ester monomer may include alkyl (meth)acrylate,(meth)acrylate having an aromatic group, heterocyclic (meth)acrylate oralkoxy (meth)acrylate. A variety of polymer components used to preparethe active energy ray-curable composition are known in the art, and theabove-described compounds may be selected, when necessary.

The reactive diluting monomer that may be included in the active energyray-curable acryl composition may be a monomer having one or two or moreactive energy ray-curable functional groups, for example, acryloylgroups or methacryloyl groups, and the (meth)acrylic ester monomer orthe multifunctional acrylate may be, for example, used as the reactivediluting monomer.

The selection of the components and a blending ratio of the selectedcomponents used to prepare the active energy ray-curable acrylcomposition are not particularly limited, and may be adjusted inconsideration of desired hardness and other physical properties of theresin layer.

For example, a resin layer having an uneven surface formed therein and aresin layer including particles may be used as the AG or SG layer. Also,another resin layer including particles having a different refractiveindex than the particles of the resin layer may also be used.

A resin layer used for formation of the high-hardness layer may be, forexample, used as the resin layer. When the anti-glare layer is formed,the components of the resin composition may not necessarily be adjustedso that the resin layer can show high hardness, but it is advantageousin that a surface-treated layer having both functions of thehigh-hardness layer and the anti-glare layer may be formed when theparticles are blended into a resin layer for forming the high-hardnesslayer.

As such, a method of forming an uneven surface on a resin layer is notparticularly limited. For example, the uneven structure may be realizedby curing the resin composition while keeping a coating layer of theresin composition in contact with a mold having a desired unevenstructure, or by blending particles having proper particle sizes with aresin composition, coating and curing the resin composition.

The anti-glare layer may also be formed using particles having adifferent refractive index than the resin layer.

According to one exemplary embodiment, the particles have a differencein refractive index from the resin layer of 0.03 or less or 0.02 to 0.2.When the difference in refractive index is extremely small, it isdifficult to induce haze, whereas, when the difference in refractiveindex is extremely high, scattering in the resin layer may often causean increase in haze, but light transmittance or contrast characteristicsmay be degraded. Therefore, suitable particles may be selected inconsideration of these facts.

The shape of the particles included in the resin layer is notparticularly limited, but may for example be a spherical, oval,polyhedral, amorphous or other shape. The particles may have an averagediameter of 50 nm to 5,000 nm. According to one exemplary embodiment,particles having an uneven surface formed therein may be used as theparticles. Such particles may for example have an average surfaceroughness (Rz) of 10 nm to 50 nm or 20 nm to 40 nm, and/or a maximumheight of protrusions formed on the surface of particles may be in arange of approximately 100 nm to 500 nm or 200 nm to 400 nm, and a widthbetween the protrusions may be in a range of 400 nm to 1,200 nm or 600nm to 1,000 nm. Such particles are highly compatible with the resinlayer, and show excellent dispersibility in the resin layer.

Examples of the particles may include various inorganic or organicparticles. Examples of the inorganic particles may include silica,amorphous titania, amorphous zirconia, indium oxide, alumina, amorphouszinc oxide, amorphous cerium oxide, barium oxide, calcium carbonate,amorphous barium titanate or barium sulfate, and examples of the organicparticles may include particles including a cross-linked oruncross-linked product formed of an organic material such as an acrylresin, a styrene resin, a urethane resin, a melamine resin, abenzoguanamine resin, an epoxy resin or a silicone resin, but thepresent invention is not limited thereto.

Neither the uneven structure formed in the resin layer nor the contentof the particles is particularly limited. For example, in the case ofthe AG layer, the shape of the uneven structure or the content of theparticles may be adjusted so that a haze value of the resin layer may bein a range of approximately 5% to 15%, 7% to 13%, or approximately 10%,and, in the case of the SG layer, they may be adjusted so that a hazevalue of the resin layer may be in a range of approximately 1% to 3%.The haze value may be measured according to the manufacturer's manualusing a hazemeter such as HR-100 or HM-150 (commercially available fromSEPUNG).

The low reflection layer such as AR or LR layer may be formed by coatinga low refractive index material. Low refractive index materials whichmay be used to form the low reflection layer are widely known in theart. All the low refractive index materials may be properly selected andused in the optical element. The low reflection layer may be formedthrough coating of the low refractive index material so that the lowreflection layer can have reflexibility of approximately 1% or less.

In order to form the surface-treated layer, materials disclosed inKorean Patent Publication Nos. 2007-0101001, 2011-0095464, 2011-0095004,2011-0095820, 2000-0019116, 2000-0009647, 2000-0018983, 2003-0068335,2002-0066505, 2002-0008267, 2001-0111362, 2004-0083916, 2004-0085484,2008-0005722, 2008-0063107, 2008-0101801 or 2009-0049557 may also beused.

The surface-treated layer may be formed using the known materials,either alone or in combination. Examples of the combination may includea case where a high-hardness layer is first formed on a surface of abase layer and a low-reflection layer is then formed on a surface of thehigh-hardness layer.

The optical element may further include a protection layer attached to abottom portion of the polarizer. FIG. 7 is a schematic diagram showingan optical element 7 further including a protection layer 71 attached toa bottom portion of a polarizer 11. For example, the protection layermay include a cellulose resin film such as a TAC (triacetyl cellulose)film; a polyester film such as a PET (poly(ethylene terephthalate))film; a polycarbonate film; a polyethersulfone film; an acryl film; apolyolefin-based film such as a polyethylene, polypropylene or cyclicolefin resin film; or a resin layer that is cured to form a hard layer,but the present invention is not limited thereto.

In addition, the optical element may further include a phase retardationlayer arranged on bottom portion of the polarizer. The phase retardationlayer may be a ¼-wavelength phase retardation layer or a ½-wavelengthphase retardation layer. In this specification, the term “¼- or½-wavelength phase retardation layer” may refer to a phase retardationelement that can phase-retard incident light by ¼ or ½ of a wavelengthof the incident light. For example, the optical element having such astructure may be effectively used as an element that is applied to anorganic light emitting diode (OLED) to give a light division functionand an anti-reflection function. For example, a polymer film which givesbirefringence through an elongation process or a liquid crystal layerformed by polymerizing a polymerizable liquid crystal compound may beused as the ¼-wavelength phase retardation layer.

Also, the optical element may further include a pressure-sensitiveadhesive layer formed on one surface of the polarizer. For example, thepressure-sensitive adhesive layer may be a pressure-sensitive adhesivelayer used to attach the optical element to an optical instrument, forexample, a liquid crystal panel of a liquid crystal display device or animage display element of a stereoscopic image display device. FIG. 8 isa schematic diagram showing an optical element 8 in which apressure-sensitive adhesive layer 81 is formed on a bottom portion of apolarizer 13.

The pressure-sensitive adhesive layer may have a storage modulus at 25°C. of 0.02 MPa or more, 0.03 MPa or more, 0.04 MPa or more, 0.05 MPa ormore, 0.06 MPa or more, 0.07 MPa or more, 0.08 MPa, greater than 0.08MPa, or 0.09 MPa or more. An upper limit of the storage modulus of thepressure-sensitive adhesive is not particularly limited. For example,the storage modulus may be 0.25 MPa or less, 0.2 MPa or less, 0.16 MPaor less, 0.1 MPa or less, or 0.08 MPa or less.

When the pressure-sensitive adhesive layer has this storage modulus, theoptical element may show excellent durability, and thus show a stablelight division property since the phase retardation property of thephase retardation layer is, for example, stably maintained for a longperiod of time under the severe conditions. Also, it is possible toprevent side effects such as light leakage in optical instruments usingthe optical element. In addition, the optical element may show excellentresistance to an external pressure or scratch due to its improvedhardness property, thereby properly maintaining reworkability.

The pressure-sensitive adhesive layer may have a thickness of 25 μm orless, 20 μm or less, or 18 μm or less. When the pressure-sensitiveadhesive layer has this thickness, the durability, hardness property andreworkability may be further improved. The pressure-sensitive adhesivelayer shows excellent physical properties as the pressure-sensitiveadhesive layer becomes thin. Here, a lower limit of the thickness is notparticularly limited, but the thickness of the pressure-sensitiveadhesive layers may be, for example, adjusted within a range ofapproximately 1 μm or more, or approximately 5 μm or more inconsideration of processability.

The pressure-sensitive adhesive layer may include an acrylpressure-sensitive adhesive, a silicon pressure-sensitive adhesive, anepoxy pressure-sensitive adhesive or a rubber-based pressure-sensitiveadhesive.

When the pressure-sensitive adhesive layer includes an acrylpressure-sensitive adhesive, the pressure-sensitive adhesive may be, forexample, formed by curing a pressure-sensitive adhesive compositionincluding a thermocurable component, an active energy ray-curablecomponent, or both the thermocurable component and the active energyray-curable component.

As such, the term “curing” may mean a change in a chemical or physicalstate of a pressure-sensitive adhesive composition to exhibit apressure-sensitive adhesive property. As such, the thermocurablecomponent and active energy ray-curable component may also refer to acomponent which is cured by application of suitable heat or irradiationof active energy rays.

The pressure-sensitive adhesive layer formed of the pressure-sensitiveadhesive composition including the thermocurable component may includean acrylic polymer cross-linked using a multifunctional cross-linkingagent.

For example, an acrylic polymer having a weight average molecular weightof 500,000 or more may be used as the acrylic polymer cross-linked usingthe multifunctional cross-linking agent. In this specification, theweight average molecular weight is a value converted from that of apolystyrene standard as measured using gel permeation chromatography(GPC). Also, unless otherwise defined in this specification, the term“molecular weight” means a “weight average molecular weight.” A polymerhaving a molecular weight of 500,000 or more may be used to form apressure-sensitive adhesive layer having excellent durability undersevere conditions. An upper limit of the molecular weight is notparticularly limited, and the molecular weight of the acrylic polymermay be, for example, adjusted within 2,500,000 or less in considerationof the durability or a coating property of a composition.

According to one exemplary embodiment, the acrylic polymer may include a(meth)acrylic ester monomer and a cross-linking monomer aspolymerization units.

For example, alkyl (meth)acrylate may be used as the (meth)acrylicester-based monomer, and alkyl (meth)acrylate containing an alkyl grouphaving 1 to 20 carbon atoms may be used in consideration of thecohesion, glass transition temperature or pressure-sensitive adhesivityof a pressure-sensitive adhesive.

Examples of such a monomer may include methyl (meth)acrylate, ethyl(meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate,n-butyl (meth)acrylate, t-butyl (meth)acrylate, sec-butyl(meth)acrylate, pentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate,2-ethylbutyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl(meth)acrylate, isononyl (meth)acrylate, lauryl (meth)acrylate andtetradecyl (meth)acrylate, which may be used alone or in combination.

In addition, the polymer may further include a cross-linking monomer asa polymerization unit. For example, the polymer may include 80 parts byweight to 99.9 parts by weight of the (meth)acrylic ester monomer and0.1 parts by weight to 20 parts by weight of the cross-linking monomeras polymerization units. As such, the term “cross-linking monomer”refers to a monomer that can be copolymerized with another monomer usedto form an acrylic polymer and provide a cross-linking functional groupto the polymer after the copolymerization. The cross-linking functionalgroup may react with a multifunctional cross-linking agent as will bedescribed later to form a cross-linking structure.

Examples of the cross-linking functional group may include a hydroxylgroup, a carboxyl group, an epoxy group, an isocyanate group or anitrogen-containing functional group such as an amino group.Copolymerizable monomers which can provide the above-mentionedcross-linking functional group in manufacture of a pressure-sensitiveadhesive resin are widely known in the art. Examples of thecross-linking monomer may include, but are not limited to, a hydroxylgroup-containing monomer such as 2-hydroxyethyl (meth)acrylate,2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate,6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate,2-hydroxyethyleneglycol (meth)acrylate or 2-hydroxypropyleneglycol(meth)acrylate; a carboxyl group-containing monomer such as(meth)acrylic acid, 2-(meth)acryloyloxy acetic acid, 3-(meth)acryloyloxypropyl acid, 4-(meth)acryloyloxy butyric acid, an acrylic acid dimer,itaconic acid, maleic acid and maleic anhydride, or anitrogen-containing monomer such as (meth)acrylamide, N-vinylpyrrolidinone or N-vinyl caprolactam, which may be used alone or incombination.

The acrylic polymer may include various other monomers as polymerizationunits, when necessary. Examples of the other monomers may include anitrogen-containing monomer such as (meth)acrylonitrile,(meth)acrylamide, N-methyl (meth)acrylamide or N-butoxy methyl(meth)acrylamide; a styrene-based monomer such as styrene or methylstyrene; glycidyl (meth)acrylate; or a carboxylic acid vinyl ester suchas vinyl acetate. Such additional monomers may be adjusted to a contentof 20 parts by weight or less, relative to the total weight ratio of theother monomers.

The acrylic polymer may be prepared by subjecting a mixture of monomersobtained by optionally selecting and blending the above-describedcomponents through a polymerization method such as solutionpolymerization, photopolymerization, bulk polymerization, suspensionpolymerization or emulsion polymerization.

Examples of the multifunctional cross-linking agent serving tocross-link the above-described acrylic polymer in the pressure-sensitiveadhesive layer may include conventional thermocurable cross-linkingagents such as an isocyanate cross-linking agent, an epoxy cross-linkingagent, an aziridine cross-linking agent and a metal chelatecross-linking agent. As such, examples of the isocyanate cross-linkingagent may include a multifunctional isocyanate compound such as tolylenediisocyanate, xylene diisocyanate, diphenylmethane diisocyanate,hexamethylene diisocyanate, isophorone diisocyanate, tetramethylxylenediisocyanate or naphthalene diisocyanate, or a compound obtained byreacting the multifunctional isocyanate compound with a polyol compoundsuch as trimethylol propane. Examples of the epoxy cross-linking agentmay include at least one selected from the group consisting ofethyleneglycol diglycidyl ether, triglycidyl ether, trimethylolpropanetriglycidyl ether, N,N,N′,N′-tetraglycidyl ethylenediamine and glycerindiglycidyl ether, examples of the aziridine cross-linking agent mayinclude at least one selected from the group consisting ofN,N′-toluene-2,4-bis(1-aziridine-carboxamide),N,N′-diphenylmethane-4,4′-bis(1-aziridine-carboxamide), triethylenemelamine, bisisoprotaloyl-1-(2-methylaziridine) andtri-1-aziridinylphosphine oxide, and examples of the metal chelatecross-linking agent may include compounds obtained by coordinating apolyvalent metal such as aluminum, iron, zinc, tin, titanium, antimony,magnesium or vanadium with acetylacetone or ethyl acetoacetate, but thepresent invention is not limited thereto.

The multifunctional cross-linking agent present in a pressure-sensitiveadhesive composition including a thermocurable component or apressure-sensitive adhesive layer formed of the composition may be, forexample, included in an amount of 0.01 parts by weight to 10 parts byweight or 0.01 parts by weight to 5 parts by weight, relative to 100parts by weight of the acrylic polymer. When a content ratio of thecross-linking agent is adjusted to a content of 0.01 parts by weight ormore, it is possible to effectively maintain cohesion of apressure-sensitive adhesive, whereas, when the content ratio of thecross-linking agent is adjusted to a content of 10 parts by weight orless, it is possible to prevent interlayer detachment or lifting frombeing caused in the pressure-sensitive adhesive interface and maintainexcellent durability. However, the weight ratio may be varied accordingto desired physical properties such as elastic modulus or inclusion ofother cross-linking structures in the pressure-sensitive adhesive layer.

The pressure-sensitive adhesive layer formed of the pressure-sensitiveadhesive composition including the active energy ray-curable componentmay include a cross-linking structure of a polymerized active energyray-polymerizable compound. The pressure-sensitive adhesive layer maybe, for example, formed by blending a compound including at least onefunctional group which can take part in a polymerization reaction byirradiation of active energy rays, such as, for example, an alkenylgroup, an acryloyl group, a methacryloyl group, an acryloyloxy group ora methacryloyloxy group to prepare a pressure-sensitive adhesivecomposition, and cross-linking and polymerizing the component byirradiating the composition with active energy rays. As such, examplesof the compound including the functional group which can take part inthe polymerization reaction by irradiation of the active energy rays mayinclude a polymer obtained by introducing a functional group such as anacryloyl group, a methacryloyl group, an acryloyloxy group or amethacryloyloxy group into a side chain of the acrylic polymer; acompound known as an active energy ray-curable oligomer in the art, suchas urethane acrylate, epoxy acrylate, polyester acrylate or polyetheracrylate; or a multifunctional acrylate as will be described later.

The pressure-sensitive adhesive layer formed of the pressure-sensitiveadhesive composition including a thermocurable component and an activeenergy ray-curable component may have both a cross-linking structureincluding an acrylic polymer cross-linked using a multifunctionalcross-linking agent and a cross-linking structure including apolymerized active energy ray-polymerizable compound.

Such a pressure-sensitive adhesive layer is a pressure-sensitiveadhesive including an interpenetrating polymer network (hereinafterreferred to as “IPN”). The term “IPN” may refer to a state where atleast two cross-linking structures are present in a pressure-sensitiveadhesive layer. According to one exemplary embodiment, the cross-linkingstructures may be present in a state of entanglement, linking orpenetration. When the pressure-sensitive adhesive layer includes theIPN, the pressure-sensitive adhesive layer may show excellent durabilityunder the severe conditions, and also may be used to realize an opticalelement having excellent workability or an excellent ability to preventlight leakage or crosstalk.

The components listed in the pressure-sensitive adhesive compositionincluding the thermocurable component, may be, for example used as themultifunctional cross-linking agent and the acrylic polymer for thecross-linking structure, which is realized by the acrylic polymercross-linked using the multifunctional cross-linking agent in thepressure-sensitive adhesive layer including the IPN.

Also, the above-described compounds may be used as the active energyray-polymerizable compound for the cross-linking structure of thepolymerized active energy ray-polymerizable compound.

According to one exemplary embodiment, the active energyray-polymerizable compound may be a multifunctional acrylate. Compoundshaving at least two (meth)acryloyl groups may be used as themultifunctional acrylate without limitation. For example, themultifunctional acrylate that may be used herein may include adifunctional acrylate such as 1,4-butanediol di(meth)acrylate,1,6-hexanediol di(meth)acrylate, neopentylglycol di(meth)acrylate,polyethylene glycol di(meth)acrylate, neopentylglycol adipatedi(meth)acrylate, hydroxyl puivalic acid neopentylglycoldi(meth)acrylate, dicyclopentanyl di(meth)acrylate,caprolactone-modified dicyclopentenyl di(meth)acrylate,ethyleneoxide-modified di(meth)acrylate, di(meth)acryloxy ethylisocyanurate, allylated cyclohexyl di(meth)acrylate,tricyclodecanedimethanol(meth)acrylate, dimethylol dicyclopentanedi(meth)acrylate, ethyleneoxide-modified hexahydrophthalicdi(meth)acrylate, tricyclodecane dimethanol(meth)acrylate,neopentylglycol-modified trimethylpropane di(meth)acrylate, adamantanedi(meth)acrylate or 9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene; atrifunctional acrylate such as trimethylolpropane tri(meth)acrylate,dipentaerythritol tri(meth)acrylate, propionic acid-modifieddipentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate,propyleneoxide-modified trimethylolpropane tri(meth)acrylate,trifunctional urethane (meth)acrylate ortris(meth)acryloxyethylisocyanurate; a tetrafunctional acrylate such asdiglycerin tetra(meth)acrylate or pentaerythritol tetra(meth)acrylate; apentafunctional acrylate such as propionic acid-modifieddipentaerythritol penta(meth)acrylate; and a hexafunctional acrylatesuch as dipentaerythritol hexa(meth)acrylate, caprolactone-modifieddipentaerythritol hexa(meth)acrylate or urethane (meth)acrylate (forexample, a reaction product of an isocyanate monomer andtrimethylolpropane tri(meth)acrylate, etc.).

Compounds having a ring structure within the molecule may be used as themultifunctional acrylate. The ring structure included in themultifunctional acrylate may be one of a carbocyclic structure orheterocyclic structure; and a monocyclic or polycyclic structure.Examples of the multifunctional acrylate having a ring structure mayinclude a monomer having an isocyanurate structure, such astris(meth)acryloxy ethyl isocyanurate, and a hexafunctional acrylatesuch as isocyanate-modified urethane (meth)acrylate (for example, areaction product of an isocyanate monomer and trimethylolpropanetri(meth)acrylate, etc.), but the present invention is not limitedthereto.

The active energy ray-polymerizable compound having the cross-linkingstructure formed in the pressure-sensitive adhesive layer including theIPN may be, for example, included in an amount of 5 parts by weight to40 parts by weight, relative to 100 parts by weight of the acrylicpolymer, but the content of the active energy ray-polymerizable compoundmay be varied when necessary.

In addition to the above-described components, the pressure-sensitiveadhesive layer may include various additives known in the art.

For example, the composition including the active energy ray-curablecomponent may further include a photoinitiator to facilitate apolymerization reaction of the components. Also, the pressure-sensitiveadhesive layer may further include at least one additive selected fromthe group consisting of a silane coupling agent, a tackifier, an epoxyresin, a curing agent, a UV stabilizer, an antioxidant, a toning agent,a reinforcing agent, a filler, an antifoaming agent, a surfactant and aplasticizer.

The pressure-sensitive adhesive layer may be formed, for example, bycoating a pressure-sensitive adhesive composition prepared by blendingthe above-described components using a tool such as a bar coater or acomma coater, and curing the coated pressure-sensitive adhesivecomposition. Also, a method of curing a pressure-sensitive adhesivecomposition is not particularly limited. For example, thepressure-sensitive adhesive composition may be cured through a processof maintaining a composition at an appropriate temperature to perform across-linking reaction of the acrylic polymer and the multifunctionalcross-linking agent, and a process of irradiating a composition withactive energy rays to polymerize the active energy ray-curable compound.When both of the process of maintaining a composition at an appropriatetemperature and the process of irradiating a composition with activeenergy rays are required to be performed, the processes may be performedsequentially or simultaneously. As such, the irradiation with the activeenergy rays may be, for example, performed using a high-pressure mercurylamp, an electrodeless lamp or a xenon lamp, and the conditions such asa wavelength or light intensity of the irradiated active energy rays maybe selected to properly perform polymerization of the active energyray-curable compound.

According to one exemplary embodiment, the pressure-sensitive adhesivelayer may have a storage modulus at 25° C. of 0.02 MPa or more, 0.05 MPaor more, greater than 0.08 MPa, greater than 0.08 MPa and 0.25 MPa orless, 0.09 MPa to 0.2 MPa, or 0.09 MPa to 0.16 MPa. For example, such apressure-sensitive adhesive layer may be a pressure-sensitive adhesivelayer including the IPN.

According to another exemplary embodiment, the pressure-sensitiveadhesive layer may have a storage modulus at 25° C. of 0.02 MPa to 0.08MPa or 0.04 MPa to 0.08 MPa. Such a pressure-sensitive adhesive may be apressure-sensitive adhesive layer including a cross-linking structure ofthe thermocurable component.

In addition, the present invention is directed to providing a method ofmanufacturing an optical element. The method of manufacturing an opticalelement according to one exemplary embodiment may include forming theliquid crystal layer on a top portion of the base layer and attaching apolarizer to a bottom portion of the base layer.

As such, the liquid crystal layer may, for example, be prepared byforming an alignment film on a base layer, forming a coating layer of aliquid crystal composition including the polymerizable liquid crystalcompound on the alignment film and polymerizing the liquid crystalcomposition in an aligned state to form a liquid crystal layer.

The alignment film may be, for example, formed using a method of forminga polymer film such as polyimide on a base layer and performing arubbing process, or coating an optically aligned compound and aligningthe optically aligned compound by irradiation with linearly polarizedlight. Various methods of forming an alignment film are known in the artin consideration of desired alignment patterns, for example, patterns ofthe first and second regions.

The coating layer of the liquid crystal composition may be formed bycoating a composition on the alignment film of the base layer using aknown method. A liquid crystal layer may be formed by aligning a liquidcrystal composition according to an alignment pattern of the alignmentfilm disposed under the coating layer and polymerizing the liquidcrystal composition.

A method of attaching a polarizer to a base layer is not particularlylimited. For example, the liquid crystal layer may be attached to thepolarizer using a method of coating the water-based adhesive compositionon one surface of the base layer or the polarizer, bonding the liquidcrystal layer and the polarizer by means of the coating layer and curingthe adhesive composition, or a method of bonding a surface of the liquidcrystal layer in which a primer layer is present with the polarizerthrough a dropping method using the water-based adhesive composition andcuring the adhesive composition.

Also, the preparation method may further include forming asurface-treated layer on a top portion of the liquid crystal layer. Assuch, a method of forming a surface-treated layer is not particularlylimited.

For example, when the resin layer is formed using the surface-treatedlayer, a resin layer may be formed by coating a liquid crystal layerwith a coating solution including a variety of the above-described resincompositions, for example, active energy ray-curable acrylic resincompositions, and curing the coating solution.

As such, the coating solution may be coated using a conventional coatingmethod such as spin coating or bar coating or a selective coating methodsuch as an ink-jet method. A method of curing a coated coating solutionis not particularly limited, and a method such as application ofsuitable heat or moisture or irradiation of active energy rays may beused according to the shapes of used compositions.

According to one exemplary embodiment, the curing may be performed, asdescribed above, in a state where a coating solution comes in contactwith a suitable mold, thereby forming desired protrusions in the resinlayer.

In addition to the above-described operations, the preparation methodmay further include forming an additional layer such as the ¼-wavelengthphase retardation layer or the pressure-sensitive adhesive layer. Theformation of the additional layer is not particularly limited.

In addition, the present invention is directed to providing astereoscopic image display device. The stereoscopic image display deviceaccording to one exemplary embodiment may include the above-describedoptical element.

According to one exemplary embodiment, the stereoscopic image displaydevice may further include a display element that can generate an imagesignal for the left eye (hereinafter referred to as an “L signal”) andan image signal for the right eye (hereinafter referred to as an “Rsignal”). In the optical element, the first and second regions of theliquid crystal layer may be arranged so that the L signal can penetratethrough one of the first and second regions and the R signal canpenetrate through the other region. As such, the optical element may bearranged so that the R and L signals can first penetrate through thepolarizer of the optical element and then enter each region of theliquid crystal layer when the R and L signals are emitted from thedisplay element.

As long as the stereoscopic image display device includes the opticalelement as a light-dividing element, a variety of methods known in theart may be applied to manufacture of the stereoscopic image displaydevice.

FIG. 9 is a schematic diagram of a device according to one exemplaryembodiment, showing a structure of the device obtained when an observercan wear the polarized glasses and observe a stereoscopic image.

For example, the device 9 may sequentially include a light source 91, apolarizing plate 92, the display element 93 and the optical element 94,as shown in FIG. 9.

As such, a direct type or edge type backlight generally used for liquidcrystal display devices (LCDs) may be, for example, used as the lightsource 91.

According to one exemplary embodiment, the display element 93 may be atransmissive liquid crystal display panel including a plurality of unitpixels which are arranged in a row and/or column direction. One or twoor more pixels are combined to form an image signal-generating regionfor the right eye for generating an R signal (hereinafter referred to asan “RG region”) and an image signal-generating region for the left eyefor generating an L signal (hereinafter referred to as an “LG region”).

The RG and LG regions may be formed in stripe shapes extending in thesame direction and alternately arranged adjacent to each other, as shownin FIG. 10, or they may be formed in a lattice pattern and alternatelyarranged adjacent to each other, as shown in FIG. 11. In the liquidcrystal layer 942 of the optical element 94, the first and secondregions correspond to the LC and RC regions, respectively, and may bearranged in consideration of the arrangement of the RG and LG regions sothat the R signal to be transmitted from the RG region can be incidentto the RC region via the polarizer 941 and the L signal can be incidentto the LC region via the polarizer 941.

For example, the display element 93 may be a liquid crystal panelincluding a first transparent substrate, a pixel electrode, a firstalignment film, a liquid crystal layer, a second alignment film, acommon electrode, a color filter and a second transparent substrate,which are arranged sequentially in a direction from the light source 91.The polarizing plate 92 may be attached to one side of the panel throughwhich light is incident, for example, one side of the light source 91,and the optical element 44 may be attached to the other side of thepanel, which is arranged opposite to the one side of the panel. Apolarizer included in the polarizing plate 92 and a polarizer 941included in the optical element 94 may be, for example, arranged so thatthe absorption axes of the two polarizers can be formed at apredetermined angle, for example, at an angle of 90°. Therefore, thearrangement of the two polarizers may allow light emitted from the lightsource 91 to penetrate through the display element 93 or be interceptedby the display element 93.

In a driving state, unpolarized light may be emitted toward thepolarizing plate 92 from the light source 91 of the display device 9. Inthe light incident to the polarizing plate 92, light having apolarization axis parallel to the light transmission axis of thepolarizer of the polarizing plate 92 may penetrate through thepolarizing plate 92 and be incident to the display element 93. Lightincident to the display element 93 and penetrating through the RG regionmay be converted into an R signal, light penetrating through the LGregion may be converted into an L signal, and the R and L signals maythen be incident to the polarizer 941 of the optical element 94.

In the light incident to the liquid crystal layer 942 through thepolarizer 941, light penetrating through the LC region and lightpenetrating through the RC region are emitted, respectively, in a statewhere the two kinds of light have different polarized states. Asdescribed above, the R and L signals having different polarized statesmay enter the right and left eyes of an observer wearing the polarizedglasses, respectively, and thus the observer may observe a stereoscopicimage.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will become more apparent to those of ordinary skill in theart by describing in detail exemplary embodiments thereof with referenceto the attached drawings, in which:

FIG. 1 is a schematic diagram showing an optical element according toone exemplary embodiment of the present invention.

FIGS. 2 and 3 are schematic diagrams showing the arrangement of firstand second regions of a liquid crystal layer according to one exemplaryembodiment.

FIG. 4 is a schematic diagram showing the arrangement of optical axes ofthe first and second regions of the liquid crystal layer according toone exemplary embodiment.

FIGS. 5 to 8 are schematic diagrams showing an optical element accordingto one exemplary embodiment.

FIG. 9 is a schematic diagram showing a stereoscopic image displaydevice according to one exemplary embodiment.

FIGS. 10 and 11 are schematic diagrams showing the arrangement of RG andLG regions according to one exemplary embodiment.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, exemplary embodiments of the present invention will bedescribed in detail. However, the present invention is not limited tothe embodiments disclosed below, but can be implemented in variousforms. The following embodiments are described in order to enable thoseof ordinary skill in the art to embody and practice the presentinvention.

Although the terms first, second, etc. may be used to describe variouselements, these elements are not limited by these terms. These terms areonly used to distinguish one element from another. For example, a firstelement could be termed a second element, and, similarly, a secondelement could be termed a first element, without departing from thescope of exemplary embodiments. The term “and/or” includes any and allcombinations of one or more of the associated listed items.

It will be understood that when an element is referred to as being“connected” or “coupled” to another element, it can be directlyconnected or coupled to the other element or intervening elements may bepresent. In contrast, when an element is referred to as being “directlyconnected” or “directly coupled” to another element, there are nointervening elements present.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of exemplaryembodiments. The singular forms “a,” “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises,”“comprising,” “includes” and/or “including,” when used herein, specifythe presence of stated features, integers, steps, operations, elements,components and/or groups thereof, but do not preclude the presence oraddition of one or more other features, integers, steps, operations,elements, components and/or groups thereof.

With reference to the appended drawings, exemplary embodiments of thepresent invention will be described in detail below. To aid inunderstanding the present invention, like numbers refer to like elementsthroughout the description of the figures, and the description of thesame elements will be not reiterated.

The physical properties of optical elements prepared in Examples andComparative Examples were evaluated as follows.

1. Evaluation of Adhesive Strength

The optical elements prepared in Examples 1 and 2 and ComparativeExamples 2 to 4, in which a surface-treated layer, a liquid crystallayer, an alignment film, a base layer, an adhesive layer and apolarizer were sequentially formed, were evaluated for adhesive strengthby peeling the polarizer at a peel angle of 90° and a peel rate of 300m/min to measure a peel strength of the polarizer to the base layer (inthe case of Comparative Example 1, a peel strength of the polarizer tothe liquid crystal layer was evaluated). A peel test was carried out bycutting a prepared optical element into pieces having a width of 20 mmand a length of 100 mm.

2. Evaluation of Durability of Liquid Crystal Layer

The durability of a liquid crystal layer was evaluated by measuring avariation of a phase difference value caused after a durability test ofthe optical elements prepared in Examples and Comparative Examples. Moreparticularly, an optical element was cut into pieces having a size of 10cm×10 cm, and then attached to a glass substrate by means of apressure-sensitive adhesive layer. The optical element was then keptunder a heat-resistant condition of 80° C. for 100 hours or 250 hours.Then, a decrease (%) in phase difference values of the liquid crystallayer before and after being kept under the heat-resistant condition wascalculated.

The results are listed in the following Table 2. As such, the phasedifference value was measured at a wavelength of 550 nm according to themanufacturer's manual using Axoscan (commercially available fromAxomatrix).

The durability evaluation criteria are as follows.

<Evaluation Criteria>

O: Variations in phase difference values of all the optical elementsafter being kept under a heat-resistant condition for 100 hours and 250hours are less than 8%.

X: A variation in phase difference value of any one of the opticalelements after being kept under a heat-resistant condition for 100 hoursand 250 hours is 8% or more.

3. Crosstalk Evaluation

A crosstalk ratio may be defined as a ratio of brightness in a darkstate and a bright state when a stereoscopic image is observed. InExamples and Comparative Examples, on the assumption that the opticalelement is applied to a stereoscopic image display device of a polarizedglasses type, a crosstalk ratio is measured using the following method.The optical element is used to constitute a stereoscopic image displaydevice as shown in FIG. 9. Then, the polarized glasses for observing astereoscopic image are disposed in a conventional observation point forthe stereoscopic image display device. As such, when a stereoscopicimage is observed by an observer, the conventional observation pointrefers to a point which is disposed away from the center of thestereoscopic image display device by a distance corresponding to 3/2 ofa length in a horizontal direction of the stereoscopic image displaydevice. At such a point, the polarized glasses are positioned on theassumption that the center of the display device is observed by anobserver. As such, when it is assumed that the stereoscopic image isobserved by the observer, the length in the horizontal direction of thestereoscopic image display device may be a length in a horizontaldirection as viewed from the observer, for example, a width of the imagedisplay device. In such an arrangement, a luminometer (equipment name:SR-UL2 Spectrometer) is arranged in rear surfaces of lenses for the leftand right eyes in the polarized glasses in a state where thestereoscopic image display device is allowed to output an L signal, andeach of the lenses for the left and right eyes is measured forbrightness. In this case, the brightness measured in the rear surface ofthe lens for the left eye is bright-state brightness, and the brightnessmeasured in the rear surface of the lens for the right eye is dark-statebrightness. After measurement of each brightness, a ratio of thedark-state brightness to the bright-state brightness ([dark-statebrightness]/[bright-state brightness]) is converted into a percentagevalue (%), which may be defined as a crosstalk ratio (Y). Also, thecrosstalk ratio may be measured in the same manner as described above,wherein the brightness in the bright and dark states may be measured ina state where a stereoscopic image display device outputs an R signal.In this case, the brightness measured in the rear surface of the lensfor the left eye is dark-state brightness, and the brightness measuredin the rear surface of the lens for the right eye is bright-statebrightness. Similarly, a ratio of the dark-state brightness to thebright-state brightness is converted into a percentage value (%), whichmay be defined as a crosstalk ratio.

4. Evaluation of Phase Difference and Refractive Index

The phase difference and refractive index of an optical element or aliquid crystal layer were evaluated according to the manufacturer'smanual using Axoscan (commercially available from Axomatrix).

5. Evaluation of Thickness and Width or Length of Optical Element

The width or length of an optical element was measured using3-dimensional equipment, Premium 600C and IView Pro program (INTEK IMSCo., Ltd.). Also, the thickness measurement was performed using aspectral reflectometer, which is equipment that is able to evaluatecharacteristics of a thin film using interference between lightreflected on a surface of the thin film and light reflected on aninterface disposed under the thin film or phase difference of thelights.

Preparative Example 1 Preparation of Liquid Crystal Layer (A)

A composition for forming an optical alignment film was coated on onesurface of a TAC base (refractive index: 1.49, thickness: 80,000 nm) sothat a thickness after coating could amount to approximately 1,000 A,and dried at 80° C. for 2 minutes in an oven. A composition used as theabove-described composition for forming an optical alignment film wasprepared by mixing a mixture of an acryl monomer and polynorbornene(molecular weight (_(Mw))=150,000) having a cinnamate group of thefollowing Formula 14 with a photoinitiator (Irgacure 907) and dissolvingthe mixture in a toluene solvent so that a solid concentration of thepolynorbornene could amount to 2% by weight (polynorbornene:acrylmonomer:photoinitiator=2:1:0.25 (weight ratio)).

Next, the dried composition for forming an optical alignment film wasaligned according to a method disclosed in Korean Patent Application No.2010-0009723 to form an optical alignment film including first andsecond alignment regions which are aligned in different directions. Moreparticularly, a pattern mask in which light-transmitting portions andlight-intercepting portions in stripe shapes having widths ofapproximately 450 μm were alternately formed in a vertical direction anda horizontal direction was disposed on an upper portion of the driedcomposition, and a polarizing plate having two regions formed thereinfor transmitting two different kinds of polarized light was alsodisposed on an upper portion of the pattern mask. Then, the compositionfor forming an optical alignment film was aligned by irradiating thecomposition with UV rays (300 mW/cm²) for approximately 30 seconds usingthe polarizing plate and the pattern mask, while transferring the TACbase 30 having the optical alignment film formed thereon at a rate ofapproximately 3 m/min. Then, a liquid crystal layer was formed on thealignment layer undergoing the alignment treatment. More particularly, aliquid crystal composition including 70 parts by weight of amultifunctional polymerizable liquid crystal compound represented by thefollowing Formula A, 30 parts by weight of a monofunctionalpolymerizable liquid crystal compound represented by the followingFormula B, and a suitable amount of a photoinitiator was coated onto theoptical alignment film to a dry thickness of approximately 1 μm, and theliquid crystal composition was aligned according to alignment of thealignment layer arranged under the liquid crystal layer. Then, a liquidcrystal layer, which includes first and second regions having differentoptical axes perpendicular to each other according to the alignment ofthe optical alignment film arranged under the liquid crystal layer, wasformed by cross-linking and polymerizing liquid crystals by irradiatingthe liquid crystals with UV rays (300 mW/cm²) for approximately 10seconds. In the liquid crystal layer, a difference between refractiveindexes in a slow axis direction and fast axis direction wasapproximately 0.125.

Preparative Examples 2 to 5 Preparation of Liquid Crystal Layer (B) toLiquid Crystal Layer (E)

Liquid crystal layers were prepared in the same manner as in PreparativeExample 1, except that a weight ratio of a multifunctional polymerizableliquid crystal compound and a monofunctional polymerizable liquidcrystal compound included in the liquid crystal composition was adjustedas listed in the following Table 1.

TABLE 1 Liquid Liquid Liquid Liquid crystal crystal crystal crystallayer (B) layer (C) layer (D) layer (E) Multifunctional 55 45 40 10polymerizable liquid crystal compound (A) Monofunctional 45 55 60 90polymerizable liquid crystal compound (B) Refractive index 0.125 0.1250.125 0.125 difference Thickness (μm) 1 1 1 1 Content unit: parts byweight Refractive index difference: difference between in-planerefractive indexes of a liquid crystal layer in a slow axis directionand a fast axis direction

Example 1

An optical element was manufactured as follows. First, in a structureprepared in Preparative Example 2, that is, a structure in which a TACbase, an alignment film and a liquid crystal layer were sequentiallyformed, the TAC base was attached to the polarizer of the polarizingplate, which includes a PVA-based polarizer having a TAC protective filmformed on one surface thereof, using a water-based PVA-based adhesivecomposition. An adhesive composition generally used to attach the TACprotective film to the PVA polarizer was used as the adhesivecomposition. A surface of the TAC base and the polarizer were laminatedusing a dropping method. In this case, the adhesive composition wascoated so that a thickness after curing a coating layer of the adhesivecomposition could amount to 1 μm, and the coating layer was maintainedat an appropriate temperature to form an adhesive layer, by which thepolarizer was attached to the surface of the TAC base. Thereafter, aconventional acrylic pressure-sensitive adhesive layer was formed on onesurface of the TAC protective film, which is a protective film of thepolarizer, to manufacture an optical element.

Example 2

An optical element was manufactured in the same manner as in Example 1,except that a structure prepared in Preparative Example 3, that is, astructure in which a TAC base, an alignment film and a liquid crystallayer (B) were sequentially formed, was used.

Comparative Example 1

An optical element was manufactured in the same manner as in Example 1,except that, in a structure prepared in Preparative Example 2, that is,a structure in which a TAC base, an alignment film and a liquid crystallayer were sequentially formed, the liquid crystal layer was attached tothe polarizer of the PVA-based polarizer having a TAC protective filmformed on one surface thereof.

Comparative Example 2

An optical element was manufactured in the same manner as in Example 1,except that a structure prepared in Preparative Example 4, that is, astructure in which a TAC base, an alignment film and a liquid crystallayer (C) were sequentially formed, was used.

Comparative Example 3

An optical element was manufactured in the same manner as in Example 1,except that a structure prepared in Preparative Example 5, that is, astructure in which a TAC base, an alignment film and a liquid crystallayer (D) were sequentially formed, was used.

Comparative Example 4

An optical element was manufactured in the same manner as in Example 1,except that a structure prepared in Preparative Example 6, that is, astructure in which a TAC base, an alignment film and a liquid crystallayer (E) were sequentially formed, was used.

The optical elements prepared in Examples and Comparative Examples wereevaluated for physical properties. The evaluation results are listed inthe following Table 2.

TABLE 2 Changes in phase difference (after being kept for 100 hours)Phase difference (nm) Durability Initial after being Adhesive of liquidphase kept at strength crystal difference heating Changes (N/cm) layers(nm) conditions (%) Example 1 3.5 or ◯ 125.4 119.7 4.5 more Example 23.5 or ◯ 120.7 114.1 5.5 more Comparative 0.3 ◯ 125.4 119.7 4.5 Example1 Comparative 3.5 or X 94.1 85.5 9.1 Example 2 more Comparative 3.5 or X77.2 69.4 10.1 Example 3 more Comparative 3.5 or — — — — Example 4 more—: A phase difference value cannot be measured since a liquid crystallayer is in a non-aligned state.

Experimental Example 1

Evaluation of Refractive Index Relationship of Liquid Crystal Layer andLight Division Property According to Thickness

In order to evaluate the refractive index relationship of a liquidcrystal layer and a light division property of the liquid crystal layeraccording to a thickness, a sample was prepared, as will be describedlater. More particularly, a phase retardation layer was formed in thesame manner as in Preparative Example 1, wherein the phase retardationlayer was prepared by forming liquid crystal layers having thicknessesof approximately 0.3 μm, 1 μm and 2.5 μm, respectively, by adjustingcompositions of a liquid crystal mixture so that a difference betweenrefractive indexes in a slow axis direction and a fast axis directioncould amount to 0.03 after formation of the liquid crystal layer. Also,a phase retardation layer was prepared in the same manner using the sameliquid crystal compound as in Preparative Example 1, wherein the phaseretardation layer was prepared by forming liquid crystal layers havingthicknesses of approximately 0.3 μm and 2.5 μm. Also, a phaseretardation layer was formed in the same manner as in PreparativeExample 1, wherein the phase retardation layer was prepared by formingliquid crystal layers having thicknesses of approximately 0.3 μm, 1 μmand 2.5 μm, respectively, by adjusting compositions of a liquid crystalmixture so that a difference between refractive indexes in a slow axisdirection and a fast axis direction could amount to 0.22 after formationof the liquid crystal layer. Thereafter, an optical element was preparedin the same manner as in Example 1 using the prepared phase retardationlayer, and crosstalk ratios obtained when the prepared optical elementand the optical element of Example 1 were used to observe a stereoscopicimage were evaluated. The results are listed in the following Table 3.

TABLE 3 Liquid crystal layers of phase retardation layers Refractiveindex difference* Thickness (μm) Crosstalk ratio (%) 0.03 0.3 79.5 0.031 45.3 0.03 2.5 10.3 0.125 0.3 36 0.125 1 0.5 0.125 2.5 177.4 0.22 0.314.6 0.22 1 30.7 0.22 2.5 121.6 Refractive index difference represents adifference between in-plane refractive indexes of a liquid crystal layerin a slow axis direction and fast axis direction.

The optical element cording to one exemplary embodiment of the presentinvention may be a light-dividing element, for example, an element thatcan divide incident light into at least two kinds of light havingdifferent polarized states. For example, the optical element may be usedto realize a stereoscopic image.

While the invention has been shown and described with reference tocertain exemplary embodiments thereof, it will be understood by thoseskilled in the art that various changes in form and details may be madetherein without departing from the scope of the invention as defined bythe appended claims.

1. An optical element comprising: a base layer; a liquid crystal layerwhich is formed on a top portion of the base layer, of which adifference between in-plane refractive indexes in a slow axis directionand a fast axis direction is from 0.05 to 0.2, which has a thickness of0.5 μm to 2.0 μm, which comprises a multifunctional polymerizable liquidcrystal compound and a monofunctional polymerizable liquid crystalcompound, the monofunctional polymerizable liquid crystal compound beingcomprised in an amount of greater than 0 parts by weight and not morethan 100 parts by weight relative to 100 parts by weight of themultifunctional polymerizable liquid crystal compound, and whichcomprises first and second regions having different phase retardationproperties; and a polarizer attached to a bottom portion of the baselayer.
 2. The optical element of claim 1, wherein the liquid crystallayer satisfies the conditions of the following Equation 1:X<8%  [Equation 1] wherein X represents a percentage of a variation in aphase difference value of the liquid crystal layer obtained after theoptical element is kept at 80° C. for 100 hours, relative to the initialphase difference value of the liquid crystal layer of the opticalelement.
 3. The optical element of claim 1, wherein the liquid crystalcompound is represented by the following Formula 1:

wherein A is a single bond, —COO— or —COO—, and R₁ to R₁₀ are eachindependently hydrogen, a halogen, an alkyl group, an alkoxy group, analkoxycarbonyl group, a cyano group, a nitro group, —O-Q-P or asubstituent of the following Formula 2, provided that at least one ofthe R₁ to R₁₀ is —O-Q-P or a substituent of the following Formula 2, ortwo adjacent substituents of R₁ to R₅ or two adjacent substituents of R₆to R₁₀ are joined together to form a benzene ring substituted with—O-Q-P, wherein Q is an alkylene group or an alkylidene group, and P isan alkenyl group, an epoxy group, a cyano group, a carboxyl group, anacryloyl group, a methacryloyl group, an acryloyloxy group or amethacryloyloxy group:

wherein B is a single bond, —COO— or —COO—, and R₁₁ to R₁₅ are eachindependently hydrogen, a halogen, an alkyl group, an alkoxy group, analkoxycarbonyl group, a cyano group, a nitro group or —O-Q-P, providedthat at least one of R₁₁ to R₁₅ is —O-Q-P, or two adjacent substituentsof R₁₁ to R₁₅ are joined together to form a benzene ring substitutedwith —O-Q-P, wherein Q is an alkylene group or an alkylidene group, andP is an alkenyl group, an epoxy group, a cyano group, a carboxyl group,an acryloyl group, a methacryloyl group, an acryloyloxy group or amethacryloyloxy group.
 4. The optical element of claim 1, wherein thepolymerizable liquid crystal compound is polymerized in a horizontallyaligned state and included in the liquid crystal layer.
 5. The opticalelement of claim 1, wherein the first and second regions have opticalaxes formed in different directions.
 6. The optical element of claim 5,wherein a line bisecting an angle formed between the optical axes of thefirst region and the second region is vertical or horizontal withrespect to the absorption axis of the polarizer.
 7. The optical elementof claim 1, wherein the polarizer is attached to the base layer by meansof a water-based adhesive.
 8. The optical element of claim 1, furthercomprising: a surface-treated layer formed on a top portion of theliquid crystal layer.
 9. The optical element of claim 8, wherein thesurface-treated layer is a high-hardness layer, an anti-glare layer or alow-reflection layer.
 10. The optical element of claim 9, wherein thehigh-hardness layer is a resin layer of which a pencil hardness is 1H ormore at a load of 500 g.
 11. The optical element of claim 10, whereinthe resin layer further comprises particles having a differentrefractive index than the resin layer.
 12. The optical element of claim11, wherein the particles have a difference in refractive index from theresin layer of 0.03 or less.
 13. The optical element of claim 1, furthercomprising: a phase retardation layer arranged in a bottom portion ofthe polarizer.
 14. The optical element of claim 1, further comprising: apressure-sensitive adhesive layer which is formed on one surface of thepolarizer, which has a storage modulus at 25° C. of 0.02 MPa to 0.08MPa, and which comprises a cross-linking structure of an acrylic polymercross-linked using a multifunctional cross-linking agent.
 15. Theoptical element of claim 1, further comprising: a pressure-sensitiveadhesive layer which is formed on one surface of the polarizer, whichhas a storage modulus at 25° C. of greater than 0.08 MPa, and whichcomprises a cross-linking structure including an acrylic polymercross-linked using a multifunctional cross-linking agent and across-linking structure including a polymerized active energyray-polymerizable compound.
 16. A stereoscopic image display devicecomprising an optical element defined in claim
 1. 17. The stereoscopicimage display device of claim 16, further comprising a display elementconfigured to generate image signals for left and right eyes, whereinthe optical element is arranged so that the image signal for the lefteye can pass through one of the first and second regions and the imagesignal for the right eye can pass through the other region.